The research program centers on determining the interface mechanics between biomaterials and bone. The objective of the research is to use experimentally determined information together with the results of finite elements stress analyses to optimize the bone-biomaterial interface design of experimental femoral head prostheses. The materials to be studied are porous materials intended for bone ingrowth and surface active bioglass materials intended to achieve chemical bonding to bone. Experimental determinations of the interfacial deformation characteristics will be made, using experimental animals, as the function of pore size and depth of porous coatings. Similar measurements will be made for the bioglass material. Finite element stress analyses will be performed using an analytical model corresponding to the geometry of the mechanical test specimens, providing a feedback loop which will be used to evaluate and refine the assumptions and validity of the model. The results from the mechanical testing and stress anaylsis phases will be used to optimize the interface design of femoral head prostheses having a porous coating and bioglass coating. Femoral head prostheses will then be fabricated, implanted and evaluated in animals.